In the critical chapter us looked at thermal equipment which carry energy. This chapter increases on this and also looks at the different ways that thermal energy is transferred in between different objects.

You are watching: Describe two energy conversions that take place when you warm a cup of cocoa in a microwave oven.

It is necessary to understand the difference between heat, together a concept, and also temperature. Temperature is a measure of how warm or cold an item is; the is a measure up of the mean kinetic power of the corpuscle of a substance. Warmth is the power transferred between two objects together a an effect of the temperature difference between them. It is additionally true when energy is transferred in between a system and also the setting as a consequence of the temperature difference in between them. Temperature is measure up in levels Celsius (°C) or levels Kelvin (K) while heat is measured in joules (J).

3.1 Heating as a move of power (0.5 hours)

3.2 Conduction (2 hours)

Tasks

Skills

Recommendation

Activity: Conduction with a metal rod

Experimentation, observation

Suggested

Investigation: perform all products conduct warm in the exact same way?

Hypothesising, investigating, evaluating

Suggested

Investigation: Which steels are the best conductors that heat?

Identifying, hypothesising, observation, writing, recording, drawing graphs. Evaluating

CAPS suggested

3.3 Convection (2 hours)

Tasks

Skills

Recommendation

Activity: Convection in water

Experimenting, observation, comparing

CAPS suggested

Activity: does smoke relocate up or down?

Observing, explaining

Suggested

Activity: Where perform I placed my radiator and also air-conditioner?

Evaluating, drawing, discussing

CAPS suggested

3.4 Radiation (1.5 hours)

Tasks

Skills

Recommendation

Activity: Radiation native a candle

Observing, examining, explaining

CAPS suggested

Investigation: Which surface absorb the most radiation?

Measuring, recording, hypothesising, identifying, observing, drawing graphs

CAPS suggested


What is the difference in between heat and also temperature? how does a heater warm up a cold room? Why can the sunlight make us warm? Why does mine cold drink come to be warm?

Heating together a deliver of energy


thermal warm temperature
In the critical chapter us looked at thermal systems. The thermal power of things is the quantity of energy it has actually inside the it, in other words, its inner energy. In a heat system, thermal power is transferred from one object to another. Warm is the transfer of thermal power from a device to its surroundings or native one object to another. This transport of energy is native the thing at a greater temperature to the thing at a lower temperature.

It is very important to recognize that, in science, heat and temperature are not the very same thing.

Heat is the move of thermal power from a device to its surroundings or native one object to one more as a result of a difference in temperature. Warm is measure up in joules (J). This is because heat is a carry of energy.

Temperature is a measure up of how warm or cold a substance feels and also it is measure up in levels Celsius (°C). Temperature is a measure of the average kinetic power of the particles in things or system. We usage a thermometer to measure up the temperature of an item or substance.

Complete the following table to summarize the differences between heat and also temperature

Unit of measurement

Symbol for unit

Heat

Temperature

Definition


here is the perfect table:

Heat

Temperature

Definition

The deliver of energy from a hotter object to a cooler object, or indigenous a device to that surroundings

A measure of how warm or cold a problem feels. A measure up of the typical kinetic energy of the particles of a substance.

Unit of measurement

Joules

degrees Celsius

Symbol because that unit

J

°C


warmth is the deliver of energy. During energy transfer, the power moves from the hotter thing to the chillier object. This way that the name is object will cool down and the cooler object will warm up. The energy transfer will proceed until both objects space at the exact same temperature.

There room 3 means in i m sorry thermal power can be moved from one object/substance come another, or indigenous a mechanism to its surroundings:

Conduction Convection Radiation

A rap song to introduce you come (and aid you remember!) conduction, convection and also radiation.


Let"s have actually a watch at these in much more detail.


Conduction


conduction conductor insulator

A suggestion to present this object is come ask learners what happens to a metal teaspoon as soon as they placed it in their warm beverage. If possible, demonstrate this briefly in class, even with a warm glass of water and a metal rod. In addition, usage a plastic teaspoon to show the distinction as plastic is an insulator.


have actually you noticed that as soon as you put a cold, steel teaspoon right into your hot cup of tea, the teaspoon handle likewise warms up after a while? have you ever before wondered exactly how this warm "moved" from the hot tea come the cold teaspoon and warmed it up? This is one method in which power is transferred and this is referred to as conduction. Let"s discover out just how it works.

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exactly how does the manage of the metal teaspoon become hot when in a cup the tea?

When energy is moved to an object, the power of the corpuscle increases. This way the particles have an ext kinetic energy and they begin to move and vibrate faster. As the particles space moving faster they "bump" into other particles and also transfer some of their power to those adjoining particles. In this way, the energy is transferred v the substance to the various other end. This procedure is called conduction. The particles conduct the power through the substance, as shown in the diagram.

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Let"s demonstrate this practically.


Conduction through a metal rod

collection this demonstration increase in front of the class as you begin to talk about conduction.

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MATERIALS:

Bunsen burner metal rod Vaseline file clips, illustration pins or security pins two wooden stands, or a ridge of books or block of hardwood to create the 2 stands ~ above either side 2 pegs

INSTRUCTIONS:

set the device up as presented in the diagram. Cover the rod in Vaseline and place it between the two stands with pegs to prevent it from rolling and hold that in place. The rod have to be prolonging past the left hand upright and the Bunsen burner placed here so the the Vaseline does not melt because of radiation from the Bunsen burner, but rather conduction follow me the steel rod. Affix the document clips or illustration pins to the rod by difficult them into the Vaseline. Irradiate the Bunsen burner and also heat the one end of the rod. Watch together the document pins or pins drop turn off one by one as the energy is performed through the rod.


INSTRUCTIONS:

her teacher will collection up the demonstration together in the chart below. Observe what happens to the pins or record clips as the Bunsen burner is lit and heat is applied to one finish of the steel rod.
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as an extension exercise you might include an additional investigation in i beg your pardon you measure the price of energy conduction along a metal rod. Repeat the experiment placing illustration pins in ~ 5cm intervals top top a long metal rod. Clamp the metal rod and also heat one end over a Bunsen burner. Usage a stopwatch to time just how long it takes because that each drawing pin to drop and record the results on a graph. This might be further extended by using various metals and also putting every the outcomes on a single collection of axes. The gradient of the graphs would give the price of warm conduction.